Faulting of Lemnos Island; a mirror of faulting of the North Aegean Trough (Northern Greece) Markos D. Tranos Department of Geology, School of Geology, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece abstract article info Article history: Received 14 July 2008 Received in revised form 3 November 2008 Accepted 19 December 2008 Available online 7 January 2009 Keywords: Fault kinematics Stress regime Transpression Lateral extrusion Back-arc extension A detailed analysis of the faulting on Lemnos Island since the Miocene was achieved by grouping the recorded meso-scale faults and their slickenlines into different groups, replacing them with Mean Representative Fault Planes (MRFP) and Lineations (MRFL), and finding the stress tensors driven to the activation of the different MRFP–MRFL pairs. The oldest recognized fault activity followed the Late Oligocene N–S contraction and uplift (D1 event) as the latter is implied by E–W to ENE–WSW buckle folds in the Upper Eocene–Lower Oligocene molasse-type sediments. It was an Early-Middle Miocene strike-slip to transpres- sion deformation (D2 event) associated with N–S contraction that also affected the Lower Miocene vol- canogenic rocks. The next fault activity was dated in Middle-Late Miocene and caused a WNW–ESE extension (D3 event). This deformation suggests that (a) during the Late Eocene–Oligocene, the North Aegean Trough was developed as a fore-arc basin between the Rhodopian magmatic arc and its subduction–accretion complex to the south, and (b) during the Late Oligocene–Middle Miocene, the North Aegean Trough, as the whole Hellenic hinterland, was subjected to the transpression s.l. deformation and lateral extrusion because of the late collisional processes between Apulia and Eurasia plates and the retreating of the Hellenic orogen. From Late Miocene to Pliocene, a NE–SW extension to right-lateral transtension (D4 event) dominated the North Aegean Trough indicating that the retreating of the Hellenic orogen was completely balanced by a back-arc extension. The deformation facilitates the westward propagation of the North Anatolian fault into the North Aegean Sea. Since the Early Pleistocene, the deformation of the North Aegean Trough is related to a NNE–SSW back-arc extension (D5) of the present-day Hellenic subduction zone and the dominant ENE– WSW to E–W faults along the North Aegean Trough function as normal to oblique right-lateral normal faults. © 2008 Elsevier B.V. All rights reserved. 1. Introduction The North Aegean Trough is an approximately 300-km-long narrow trough in the northern part of the Aegean Sea (Fig. 1) that can be readily differentiated into the NE–SW trending Sporades basin in the west and the ENE–WSW trending Saros Trough in the east, since both possess different orientations and morphotectonic features (Lyberis, 1984; Tranos, 1998). It is located in the internal part of the Hellenic orogen and more precisely along the Tethyan Ocean suture zone (Axios zone in Greece and Intra-Pontide suture zone in Turkey) as the later runs by the southern edges of the Hellenic hinterland (Mountrakis, 2006)(Fig. 2). The North Aegean Trough reaches the depth of about 2 km and has been accumulated sediments from the Eocene up to the present (Lalechos, 1986; Roussos, 1994). These sediments have been disrupted by a magmatic episode dated in the Early Miocene (Fytikas et al., 1984; Innocenti et al., 1994). The last three decades a considerable effort has been made trying to answer several issues concerning the nature of the North Aegean Trough. However, because the trough is entirely submarine, the research carried out based mainly on seismological, geophysical, geo- detic and bathymetric data. For the same reason the only published works based on geological data are those of Lyberis (1984), Mercier et al. (1989) and Pavlides et al. (1990). As a result, the North Aegean Trough is tried to be described in the present-day tectonic framework of the region into which (a) the present-day Hellenic subduction zone, (b) the westward movement of the Anatolia and the (c) collision between Apulia and Eurasia along the Ionian Sea dominate. More precisely, (a) focal mechanisms of large strike-slip earthquakes of magnitudes up to M=7.5 (Papazachos and Kiratzi, 1996; Papazachos et al.,1998; Papadimitriou and Sykes, 2001; Kiratzi, 2002; Karakostas et al., 2003), (b) latest GPS measurements (Le Pichon et al., 1995; Reilinger et al., 1997; Kahle et al., 1998; McClusky et al., 2000) that established the recent large-scale kinematics of the different crustal parts, and (c) seismic profiles (Mascle and Martin, 1990; Roussos and Lyssimachou, 1991) indicate that right-lateral strike-slip movements along the North Aegean Trough are ongoing. Thus, the North Aegean Trough has long been considered as a large seismogenic structure that represents the western propagation of the right-lateral strike-slip North Anatolian Tectonophysics 467 (2009) 72–88 E-mail address: tranos@geo.auth.gr. 0040-1951/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.tecto.2008.12.018 Contents lists available at ScienceDirect Tectonophysics journal homepage: www.elsevier.com/locate/tecto